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Rear brake master cylinder swap |
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tfcoulson
Moto2 racer
Joined: 23 Oct 2016 Location: Ireland Status: Offline Points: 165 |
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Topic: Rear brake master cylinder swapPosted: 04 Mar 2024 at 08:13 |
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Just rode to work and noticed the bike really slowing down quick when off the throttle, then noticed a lot of travel on the rear brake - turns out my master cylinder is leaking.
Has anyone replaced the Aprilia version with something different? I don't particularly want to go second hand gen1 and also don't really want to go with something Aprilia designed for the rear brake, seeing as it seems to have a habit of being rubbish. |
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tfcoulson
Moto2 racer
Joined: 23 Oct 2016 Location: Ireland Status: Offline Points: 165 |
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Posted: 04 Mar 2024 at 08:23 |
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Ah maybe Ill just go for a rebuild!
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Spoonz
Admins Group Joined: 11 Feb 2008 Location: North Devon Status: Offline Points: 10957 |
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Posted: 04 Mar 2024 at 10:35 |
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It’s a Brembo unit so not a bad design just poorly implemented. If you don’t want to relocate it via rearsets, I would repair it or fit a used item. If you relocate it, fit an rsv4 unit.
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twinfan
Premium Member Joined: 01 May 2015 Location: Kent Status: Offline Points: 254 |
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Posted: 04 Mar 2024 at 13:15 |
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I have an RSV4 unit on mine attached to AP rearsets and the system works great
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on my licence it says "tear down the dotted line" so I DO!
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legend88
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Joined: 18 Aug 2013 Location: Newcastle Status: Offline Points: 6699 |
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Posted: 05 Mar 2024 at 07:48 |
Me too, a definite improvement: ![]() |
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snowman
Premium Member Joined: 27 Oct 2010 Location: Romsey area Status: Offline Points: 1411 |
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Posted: 06 Mar 2024 at 13:36 |
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I will do that on mine I think .
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tfcoulson
Moto2 racer
Joined: 23 Oct 2016 Location: Ireland Status: Offline Points: 165 |
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Posted: 06 Mar 2024 at 18:28 |
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It actually just looks like it might have been the hjc? tube I have. Removed and re-tightned/bled it and will see how it goes. Might need to snip off the bottom bit thats a bit crushed from where its been clamped on if it keeps being an issue. I've already got the AP rearsets so couldnt use the original resevoir. That rsv4 one looks good actually. ...It also looks alot less rusty in that area
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IanG
Premium Member Joined: 04 Oct 2010 Location: N Wales Status: Offline Points: 10767 |
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Posted: 10 Mar 2024 at 14:37 |
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Sorry,get the gist now,you didn't have an original res? As of course you can use the original res with the AP rearsets. Easy and tidily in fact,I thought about one of those integral res units but decided against it on two counts. a) I'm tight Why buy something new that's not needed and..b) They look to damn close to the s/arm for comfort to me and I'm using a brand new s/a. I use the original master and res on both my Mille and Gen2 Tuono while using AP rearsets on both, although tbh I don't find any difference in rear braking before or after,I can still lock the rear wheel and never had any issues with bleeding or fade when things were standard. One thing I did do which may have helped when first bleeding after splitting the system was when I replaced the brake line for a new HEL unit I specced it slightly longer and fitted it to the lower bleed nipple posn on the caliper with the bleed relocated to the upper posn. No need for any of this stupid remove the caliper and hold it up by the seat nonsense. You can bleed both the clutch and the rear brake easily with no issues and with only a couple of res fills by just doing the job correctly in the first place. I despair watching some modern 'technicians' they haven't got a clue if they don't have access to pressure or vac bleeding aids, let gravity do the hard work. ![]() ![]() These were 'dry build' pics I'm now using a new Smoked Res to match the bar units and the caliper has had a complete overhaul with new fasteners throughout and and new seals etc. |
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www.apworkshops.co.uk
www.apriliaforum.co.uk www.apriliaownersclub.co.uk Looking forward to the next track day |
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tfcoulson
Moto2 racer
Joined: 23 Oct 2016 Location: Ireland Status: Offline Points: 165 |
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Posted: 11 Mar 2024 at 21:44 |
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I didnt think the original fit, thought there would be a bit of a clearance issue. Have you got any washers or anything attaching it to the heel guard? The HJC unit clouds up as well from the brake fluid, not the best piece of kit. I have a spare HEL line I think (probably not longer but seeing as I didnt even realise I had ordered it and then ordered a goodridge who knows!).
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IanG
Premium Member Joined: 04 Oct 2010 Location: N Wales Status: Offline Points: 10767 |
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Posted: 11 Mar 2024 at 21:55 |
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Regarding spacers or washers I'm sorry but I can't remember, it shouldn't need any as the rearsets were designed to be a straight swap as I understand it.. I do seem to recall slightly relieving either a clearance hole or or the side of a counterbore slightly to enable a straighter actuating rod run though. I do remember making an alloy bobbin to mount the res on I might have another pic of the install somewhere,I'll have a search
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www.apworkshops.co.uk
www.apriliaforum.co.uk www.apriliaownersclub.co.uk Looking forward to the next track day |
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IanG
Premium Member Joined: 04 Oct 2010 Location: N Wales Status: Offline Points: 10767 |
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Posted: 11 Mar 2024 at 22:14 |
![]() It does look as though I may have used a stainless washer between the cylinder and mount, it could be that the spotfacing on the cylinder fouled slightly and needed a standoff,it was a few years ago now and the fine details escape me. I could have a look when the rains stop and I can get to my garage again. |
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www.apworkshops.co.uk
www.apriliaforum.co.uk www.apriliaownersclub.co.uk Looking forward to the next track day |
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tfcoulson
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Joined: 23 Oct 2016 Location: Ireland Status: Offline Points: 165 |
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Posted: 14 Mar 2024 at 20:49 |
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Yep it definitely needs some sort of washer there otherwise the roundness of the pot sticks into the heel guard too much.
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V60
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Joined: 18 Feb 2023 Location: North East Status: Offline Points: 14 |
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Posted: 28 Mar 2024 at 12:13 |
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That green pipe is absolute dog sh!t.
It sweats like crazy and absorbs moisture from the atmosphere. I went through 2 separate ones in 2 weeks before I binned them and used the original reservoir. No idea why they're still being sold.
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legend88
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Joined: 18 Aug 2013 Location: Newcastle Status: Offline Points: 6699 |
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Posted: 28 Mar 2024 at 13:03 |
Weight saving on race bikes that only go an hour between bleeds. That's the only reason they exist. And as you say, completely crap and potentially dangerous on road bikes but so many people are so blinded by 'Race bling' that they don't even think anything through. |
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V60
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Joined: 18 Feb 2023 Location: North East Status: Offline Points: 14 |
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Posted: 28 Mar 2024 at 16:02 |
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The Honda forums are full of folk complaining about them there too.
It makes zero sense that a receptacle for storing brake fluid reacts badly to said brake fluid and is porous to boot.. bonkers!
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426hemi
Premium Member owner of the big bore! Joined: 30 Mar 2012 Location: cannock Status: Offline Points: 5795 |
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Posted: 28 Mar 2024 at 18:25 |
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If you’re going to use pipe for the reservoir use the tygon.
https://www.ebay.co.uk/itm/111215279138?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=cIQwD279Q8a&sssrc=2349624&ssuid=ildoydmaqc-&var=&widget_ver=artemis&media=COPY |
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redratbike
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The Collector Messiah Joined: 07 May 2008 Status: Offline Points: 16331 |
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Posted: 28 Mar 2024 at 18:35 |
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i run an rsv4 master cylinder with a built in reservoir … KTM items also work and probably cheaper
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Fitz
Moto GP Alien
Joined: 23 Apr 2010 Location: Harrogate Status: Offline Points: 344 |
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Posted: 26 May 2024 at 10:31 |
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I got a KTM unit is the same Brembo unit as on the RSV4 but with out the tax !! and loads on eBay as it is used on lots of different bike models
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